Variable flow fluid pump

ABSTRACT

A pump assembly including a resilient dome attached to a base plate, which together define a chamber. A flapper, supported on a raised center boss on the base plate, seats against a raised annular valve seat to selectively expose fluid inlet apertures in the base plate. The dome has a one-way fluid outlet valve. Dome compression seals the flapper against the valve seat and expels fluid through the fluid outlet valve. Release of the dome allows the outlet valve to close, and the dome regain its original shape, thereby creating a vacuum force that unseats the flapper and draws fluid into the chamber via the fluid inlet apertures. The pump assembly can be made for a variety of fluid densities and viscosities by varying the material and thickness of the flapper, the heights of the valve seat and the center boss, and the size and number of the fluid inlet apertures.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional patent application Ser. No. 60/834,920 filed Aug. 2, 2006, the entire contents of which are incorporated herein by reference.

BACKGROUND

This invention relates to valves, and more particularly to valves which are adapted to control fluid flow into a chamber of an inflatable bladder.

SUMMARY OF THE INVENTION

The fluid pump of the invention provides a versatile system capable of pumping fluids having a variety of densities and viscosities. The pump assembly includes a resilient dome attached at its periphery to a base plate, which together define a chamber. The base plate has a raised annular valve seat and a raised center boss which supports a flapper thereon, the flapper capable of sealing against the valve seat to selectively open or close a plurality of fluid inlet apertures in the base plate. A fluid outlet check valve is connected in fluid communication with the dome. Compression of the dome causes the flapper to seal against the valve seat and expels fluid from the chamber out through the fluid outlet valve. Release of the dome enables the fluid outlet valve to close, and enables the dome to return to its original shape, thereby creating a vacuum force that unseats the flapper and draws fluid into the chamber via the fluid inlet apertures. The pump assembly can be made to accommodate a variety of fluid densities and viscosities by varying the material and thickness of the flapper, the respective heights of the valve seat and the center boss, and the size and number of the fluid inlet apertures.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, in which like reference numerals indicate corresponding parts in all views:

FIG. 1 is a cross-sectional side view of an exemplary pump in an at-rest state.

FIG. 2 is a cross-sectional side view of the pump of FIG. 1 in a compression or dispensing stroke.

FIG. 3 is a cross-sectional side view of the pump of FIG. 1 in a recovery mode.

FIG. 4 is a top view of the base plate of the pump of FIG. 1.

FIG. 5 is a cross-sectional side view of the base plate and flapper valve of the pump of FIG. 1 prior to assembly.

DESCRIPTION OF THE EMBODIMENTS

A description of the embodiments of the present invention will now be had by way of example, and not limitation, with reference to FIGS. 1 through 5.

FIGS. 1 and 4-5 show the structural details of an embodiment of the invention. FIG. 1 is a cross-sectional side view of a pump assembly 10 in an at-rest state. Pump assembly 10 includes a resilient dome 12. The resilient dome 12 may be made from a low durometer thermoplastic material, such as a urethane or an olefin (e.g. ethylene or polypropylene), though this list of materials is considered merely illustrative, and not limiting. Dome 12 is substantially hemispherical in shape and has a flange 13 at a lower end thereof which is received under film 18 of an inflatable bladder to which the pump assembly 10 is to be secured. Flange 13 of dome 12 is secured to a base plate 14, the dome 12 and base plate 14 together creating a chamber within the pump assembly 10.

Base plate 14 is typically molded from a high durometer thermoplastic material, such as a urethane or an olefin (e.g. ethylene or polypropylene), though, once again, this list of materials is considered merely illustrative, and not limiting. Details of base plate 14 can be seen in FIGS. 4 and 5. Base plate 14 has a valve seat 24 in the form of a raised annular ridge extending up from a flat lower surface of the base plate 14. In the center of the annulus of the valve seat 24 is a raised element comprising a circular center boss 23, and extending up from the center boss 23 is a flapper mount 22. Extending through the base plate 14 in the area between the annular valve seat 24 and the center boss 23 are a plurality of fluid inlet apertures 26, typically four to six (see FIG. 4). The number and size of the fluid inlet ports is selected depending on the properties of the fluid being dispensed, and the volume of and/or speed with which the fluid is to be moved.

Mounted on the flapper mount 22 is a flapper 16. Flapper 16 is a substantially annular flat disk, typically die cut, from almost any thermoplastic or thermosetting material, including a wide variety of rubbers and silicones, as well as semi-rigid plastic films of various thicknesses. The material of the flapper 16 must be compatible with whatever fluid is being pumped. The thickness and stiffness of the flapper 16 are selected to give a desired response for the particular fluid being pumped.

Connected to a lower portion of the dome 12 that is located within the bladder when the pump is mounted to the bladder is a fluid outlet valve 20 in fluid communication with the pump assembly chamber. Fluid outlet valve 20 is a check valve and may be implemented using a valve such as that disclosed in U.S. Pat. No. 5,564,143. Any suitable check valve known in the art can be used. The outlet valve 20 may lead to an evacuation channel external to film 18 to direct fluid out of the bladder.

As can be seen in FIG. 5, the flapper 16 is placed on the flapper mount 22 of the base plate 14, which initially has a cylindrical shape of a uniform first diameter. After the flapper 16 is placed on the flapper mount 22, the free end of the flapper mount 22 is altered so that it forms a button having a second diameter, which is larger than the first diameter, to retain the flapper 16 thereon. Attachment of the flapper 16 to the flapper mount 22 of the base plate 14 can be accomplished mechanically using heat or sonic energy. As mentioned above, the material and the thickness of the flapper 16 are selected to provide a desired response to the particular fluid to be pumped. In designing the base plate 14, there are several features whose dimensions are selected based upon the particular fluid to be pumped. The center boss 23 of the base plate 14 serves as a height adjuster. The height h1 of the center boss 23 and the height h2 of the valve seat 24 are each selected based on the properties of the fluid to be pumped. Whether h2 is bigger than, the same as, or less than h1 will affect how difficult it is for the seal between the flapper 16 and the valve seat 24 to be released, with an easy release being desirable for thicker fluids, and a tighter release being preferable for thinner fluids. By providing a valve seat 24 that is raised above the lower surface of the base plate 14, the contact area between the flapper 16 and the valve seat 24 is reduced, making release of the flapper 16 from the valve seat 24 easier, and enabling the ease with which it is released more controllable as compared to a valve having a flat flapper 16 contacting a planar surface over most of its surface when closed (not shown). Further, the resiliency of the flapper 16 may be controlled by selecting certain materials and/or dimensions of the flapper 16. The resiliency of the flapper affects the amount of deflection of the flapper 16 and thus the flow rate of fluid through the fluid inlet apertures 26.

In operation, a user places a digit, such as a thumb or finger, on dome 12 and applies a compressive downward force, shown in FIG. 2 as arrow C. Pressing the dome 12 downward towards base plate 14 exerts pressure, shown as arrows P, on the flapper 16 which causes the flapper 16 to seal against valve seat 24, thereby preventing the fluid from exiting the pump assembly 10 via fluid inlet apertures 26. Fluid is, instead, forced out of the fluid outlet valve 20. Upon release of the compressive force by the user on the dome 12, due to the shape and resilient nature of the material of the dome, the dome will return to its original shape, creating a vacuum force within the dome, shown in FIG. 3 by the arrow V. With the fluid outlet check valve 20 closed, this vacuum force pulls the flapper 16 away from the valve seat 24 and draws fluid into the chamber of the pump assembly 10 via the fluid inlet apertures 26. Once the dome 12 returns to its original shape, the flapper 16 reseats itself on the valve seat 24 and the pump assembly returns to the at-rest state shown in FIG. 1 where no fluid is flowing either into or out of the pump assembly 10.

While this invention has been described with reference to one or more embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the spirit or scope of this invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention. 

1. A fluid pump comprising: a dome having a flange; a base plate secured to the flange at a periphery of the base plate; the base plate including a flapper mount for receiving a central portion of a flapper; the base including a valve seat for engaging a peripheral portion of the flapper to form a fluid seal; the base plate including an inlet aperture positioned beneath the flapper; and an outlet valve in fluid communication with the dome.
 2. The fluid pump of claim 1 wherein: the flapper mount is positioned on a raised boss extending from the base plate.
 3. The fluid pump of claim 1 wherein: a height of boss versus a height of valve seat is set to control fluid flow through the pump.
 4. The fluid pump of claim 1 wherein: the inlet aperture includes a plurality of inlet apertures.
 5. The fluid pump of claim 4 wherein: the size and number of inlet apertures is set to control fluid flow through pump.
 6. The fluid pump of claim 1 wherein: dome is made from a low durometer thermoplastic material
 7. The fluid pump of claim 1 wherein: the dome is substantially hemispherical.
 8. The fluid pump of claim 1 further comprising: a flapper mount extending up from the boss, the flapper mount receiving the flapper. 